>> reporter: turning out, there is a science to getting those priceless reactions. one study found, pricier gifts don't translate into greater appreciation. exhibit one, the kitten. >> oh my god! >> reporter: the key, studies show, is getting into the head of the recipient. and in the head of a kid, this electric guitar is a good idea. experts say you should give the recipient exactly what they say they want, not what you think they should want. >> what the heck is that? that's not toys, that's books! >> reporter: in other words, stick to the list. and reap the rewards. sharyn alfonsi, abc news, new york. >> and thank you for watching. "nightline" will be along later. we leave you tonight with the national christmas tree. 28 feet tall, the lights just switched on. good night. /jok;v <o